The GMC and the Medical Defence Union (MDU) advised GPs to explain this to patients who had previously refused the vaccine.

This year’s trivalent seasonal flu jab contains swine flu antigens because experts believe swine flu will circulate this winter. A DoH information leaflet has been produced to explain the contents of the vaccine.

GMC assistant director of standards Jane O’Brien told GP it would be wise to explain this to patients who previously rejected the vaccine.

‘If you know a patient has previously refused the single swine flu vaccine, it's likely they would want to know this year's seasonal vaccine includes the swine flu strain,’ she said. However, GPs must be careful not to put pressure on patients to accept advice.

A DoH spokesman said: ‘Like previous years, this year's seasonal flu vaccine contains protection against three strains of influenza in a single dose. Because it is a single vaccine, only one consent is needed from patients.’

But Suffolk GP Dr Fergal O’Driscoll said: ‘Lots of patients refused that specific component last year when offered it. I’d be anxious about [including this] without specific consent for that component among patients who explicitly refused it last year.’

Dr O’Driscoll said it would be a ‘dangerous precedent’ for the profession not to check these patients knew the vaccine contained swine flu antigens.

GPC negotiator Dr Peter Holden said ‘there is always the possibility’ vaccine uptake could be hit, although any fears over the vaccine were unfounded.

Dr Udvitha Nandasoma, a MDU medico-legal adviser said GPs ‘may also wish to check patients understanding of the vaccine before they administer it’ and include this in patient notes.

RCGP immunisation lead Dr George Kassianos said: ‘We should not lose any opportunity to discuss the contents of this year’s influenza vaccine.’